This invention relates generally to valves usable to deliver water from housing or building plumbing lines. More particularly, it concerns improvements to such valves, simplifying their construction, and enhancing their performance.
There is need in such valves for improvements associated with blocking or checking back flow where reverse flow pressure may build up. Also, there is need in such valves for separating the built-up back flow pressure, from the potable water supply as during checking or blocking of such back flow to the building plumbing. Such back flow, if unchecked, could contaminate water in that plumbing. There is also need for such separation in the form of a chamber, or air gap, between two check valves, to ensure against cross-contamination between a potable water supply and a source of back pressure.
The existing hydrants rely on a single check valve as the only barrier between pressure that can develop in a supply duct, such as a hose, with no potable water, and a potable water supply. If and when that single check valve fails, possibly contaminated water in the hose will flow into the potable water supply.
It is a major object of the invention to provide an improved, compact, simple, highly effective back flow preventing valving assembly, meeting the above need. Basically, the assembly includes:
a) a body defining a flow chamber having a side outlet,
b) a control adjustable to move lengthwise in the chamber,
c) a first valving part carried by the control and movable to advance and retract relative to a second valve part on the body, thereby to provide a first check-valve to block reverse flow of fluid through the chamber,
d) and a second check-valve located proximate the side outlet to pass forward fluid flow from the chamber, and to block reverse flow of fluid to the chamber, via that side outlet.
Further objects include the location of the control such as a rod in the chamber to project toward said first check valve, the second check valve sidewardly offset from the rod and the rod being movable to advance and retract in response to turning of a handle in opposite directions; provision of a flow chamber side extension sidewardly offset from the rod, the second check valve located in that chamber side extension; and first and second body portions which are interconnected, the first body portion carrying the first check valve, and the second body portion carrying the second check valve.
Yet another object includes provision of the second check valve to comprise tubular body structure having main passage structure between flow entrance and exit ports; the body structure having a port communicating with the passage structure; first and second diaphragms carried by the body structure to be exposed to flow in the passage structure; the second diaphragm being typically movable to allow in-flow of air through a side port when a stopper and the first diaphragm block back flow of fluid through the main passage structure.
An additional object is to provide a safety valve apparatus that includes:
a) first and second valving assemblies, each including a check valve,
b) the first valving assembly having a primary side which is an inlet side to which potable water is supplied, and a secondary side,
c) the second valve assembly having a primary side, and a secondary side which is a discharge side to which back pressure may be supplied,
d) and a barrier chamber communicating between said first assembly discharge side and said second assembly primary side, for blocking cross-contamination between potable water at said first assembly primary side, and liquid at said second assembly secondary side.